ALCYONARIA — J. A. THOMSON AND DORIS L. MACKINNON. 683- 



are smaller than those described for P. penna, and are smoother 

 and of more simple outline. Tlie chief point of difterence, how- 

 ever, lies in the mode of branching, which in P. penna is close 

 and typically feather-like. Versluys^ speaks of as many as 

 twenty-three twigs on each side of a branch in a stretch of 5 cm.; 

 these twigs, moreover, are never longer than 3 cm. and are always^ 

 unbranched. 



Locality. — Eleven miles east of Broken Bay. 



PLUMARELLA THETIS, sp. nov. 



(Plate Ixvi., fig. 5 ; pi. Ixviii., fig. 6 ; pi. Ixxvi.) 



Stations 34, 40, 42, 47, 48, 53. 



This handsome new species is well represented by dried speci-- 

 mens ; two small pieces are preserved in spirit. 



The colonies are typically feather-like. The long, frond-like 

 branches bear on each side a row of alternating twigs. These 

 twigs occasionally branch in the same pinnate manner, but 

 usually remain simple. The polyps rarely occur on two sides of 

 the twigs ; usually they are arranged all over the twigs in close 

 spirals. On the larger branches they may be confined to two 

 sides, or they may be scattered indefinitely over the whole surface. 



None of the specimens show the basal portion. The most 

 richly-branched colony has a height of 32 cm., with a width of 

 53 cm. The stem has a diameter of 5 mm. The twigs average 

 3-4-5 cm. in length, with a diameter of 2 mm. There are about 

 fourteen twigs on each side in a length of 5 cms. i^V'4 



Some of the colonies are much more heavily built. A single 

 frond is 43 cm. long, with a diameter of 5'5 mm. at the base. 

 The twigs in this case are 8-10 cm. long, with a diameter of 

 2-3 mm., and only seven to eight occur in each row in a length of 

 5 cm. 



The polyps are very closely crowded over the twigs. Their 

 average length is 1 mm. The calyx scales are arranged in longi- 

 tudinal rows, of which the abaxials alone are complete. These 

 consist of about six relatively large, overlapping scales. The 

 adaxial rows are reduced to about one small scale, and the adaxial- 

 laterals are also very few in number and are overlapped by the- 

 abaxial-laterals. The calyx scales are broad, shield-like and fan- 

 like, with entire margins around the overlapping portion; the 

 overlapped portion contains the nucleus, surrounded by numerous 

 finely-tuberculate warts. The clear border between the outer 

 margin and the waned portion bears radiating ridges. The 

 following measurements were taken of the length and breadth of 



